1. Field
The presently disclosed subject matter relates to stereographic display apparatuses for portable electrical equipments and to vehicle headlights including an automatic level controller. More particularly, the disclosed subject matter relates to stereographic display apparatus, which can provide favorable stereographic displays to viewers regardless of a position thereof, even if they incline due to hand movement and the like, and to vehicle headlights, which can form light distributions in a useful direction for drivers, even when they move in various directions with reference to a road due to road conditions, etc.
2. Description of the Related Art
Stereographic display apparatuses can provide the human eye with a stereographic display by projecting an image having a disparity viewed from each of both eyes on a flat panel screen. Methods for the stereographic display may be divided into either a method using glasses or a method not using glasses. Because the method using glasses may be bothersome to beholders because of the glasses, the method not using glasses has been developed in recent years.
Conventional stereographic display apparatuses not using glasses, for example, are disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open JP2001-66547), Patent Document No. 2 (International Publication No. WO 2004/027492), etc. FIG. 10 is a schematic structure showing a conventional stereographic display unit, which is disclosed in Patent Document No. 2.
The conventional stereographic display unit includes: a light guide 72 having a light-emitting surface 72a and a pair of light incoming surfaces, which face with respect to each other; a pair of light sources 71a and 71b located adjacent a respect one of the light incoming surfaces of the light guide 72, respectively; a prism sheet 73 having a triangular prism array and a cylindrical lens array being located adjacent the light-emitting surface 72a of the light guide 72 so that the triangular prism array faces the light-emitting surface 72a of the light guide 72, the triangular prism array extending in substantially parallel with the light incoming surfaces of the light guide 72, the cylindrical lens array located opposite the triangular prism array of the prism sheet 73, and each one of the cylindrical lens array being located in substantially parallel with a respect one of the triangular prism array; a transmission-type display panel 74 located adjacent the cylindrical lens array of the prism sheet 73; and a synchronous driving means 75 configured to emit light emitted from each of the light sources 71a and 71b from the transmission-type display panel 74 at a angle corresponding to a binocular display in synchronization with a binocular parallax image, which is alternatively displayed from the transmission-type display panel 74.
Thereby, the conventional stereographic display unit can provide the human eye with a stereographic display without glasses by projecting light emitted from each of the light sources 71a and 71b from the transmission-type display panel 74 at the angle corresponding to the binocular display in synchronization with the binocular parallax image, which is alternatively displayed from the transmission-type display panel 74.
However, when a viewer sees the stereographic display depicted on the transmission-type display panel 74 from a rightward direction or from a leftward direction relative to a front of the display panel 74, the conventional stereographic display units such as those disclosed in Patent Documents No. 1 and No. 2 may not easily perform such display because the synchronous driving means 75 freely varies positions of the stereographic display projected on the transmission-type display panel 74 in accordance with an angle of gradient, which is caused by hand movement, etc.
Especially in portable electrical equipments such as a mobile phone, a portable terminal, a portable personal computer, a portable game console, each of the display devices for the portable electrical equipment may not be always located in front of the viewer. Rather position relations between the viewer and the display devices for the portable electrical equipment should be subject to changes in accordance with hand movement, a pose of the viewer, etc. In these cases, it may be difficult for the viewer to enjoy the stereographic display under favorable conditions as usual.
In addition, problems may also be caused in headlight systems when a vehicle headlight includes an automatic level controller. The vehicle headlight including the automatic level controller may emit light in a light-emitting direction thereof so as to maintain at a constant angle with reference to various road surfaces in order to prevent giving a glare type light to an incoming vehicle and the like, even if a vehicle incorporating the above-described headlight suddenly inclines due to road conditions, etc. A conventional vehicle headlight including an automatic level controller, for example, is disclosed in Patent Document No. 3 (Japanese Patent Application Laid Open JP2004-314856).
FIG. 11 is a schematic structure showing a conventional vehicle headlight including an automatic level controller, which is disclosed in Patent Document No. 3. The conventional vehicle headlight includes: a high speed bus (HB) and a low speed bus (LB) used as a vehicular local area network (LAN); a gate way 81 connecting between HB and LB; an human interface 82 connecting to the HB, and also including a switch to turn on and turn off the vehicle headlight; a three dimensional gyro sensor 84 configured to detect angle rates in three dimensional directions of the headlight, and connecting to the LB; an inclined angle table 83 connecting to the gate way 81, and storing relations between inclined angles of a vehicle incorporating the headlight detected by the three dimensional gyro sensor 84 and light-emitting directions of the headlight as a data table; a lighting unit 87 including a supporting frame 71, a first gear 61, a second gear 62 and an actuator 60, the lighting unit 87 attached to the supporting frame 71, in which a first axis of the supporting frame 71 is attached to the first gear 61, and a second axis of the supporting frame 71 is attached to the second gear 62 while the first gear 61 gears the second gear 61, the actuator 60 attached to the first gear 61 and configured to rotate the second gear 62 via the first gear 62; and a controller 5 configured to operate the actuator 60 in accordance with a control signal output from the gate way 81.
As described above, the conventional vehicle headlight includes the gate way 81, which determines a light-emitting direction and an amount of light emitted from the lighting unit 87 in accordance with the inclined angles of the vehicle detected by the gyro sensor 84, and the controller 85 to receive the control signal output from the gate way 81 via the LB. Therefore, the conventional vehicle headlight enables the lighting unit 87 to vary the light-emitting direction and the amount of the light using the gate way 81 and the controller 85 in accordance with the inclined angles of the vehicle detected by the gyro sensor 84.
However, the conventional vehicle headlight varies the light-emitting direction and the amount of the light by moving the lighting unit 87 having a movable structure, and therefore should become a headlight system having a complex structure due to at least to the movable structure for the lighting unit 87. In addition, when the conventional vehicle headlight has been used for a long time under an inhospitable environment, the long inhospitable environment may result in gradual deterioration of the movable structure
The above-referenced Patent Documents and additional Patent Documents are listed below and are hereby incorporated with their English specifications and abstracts in their entireties.    1. Patent Document No. 1: Japanese Patent Application Laid Open JP2001-66547    2. Patent Document No. 2: International Publication No. WO2004/027492    3. Patent Document No. 3: Japanese Patent Application Laid Open JP2004-314856    4. Patent Document No. 4: Japanese Patent Application Laid Open JP2011-081985    5. Patent Document No. 5: Japanese Patent Application Laid Open JP2011-145571    6. Patent Document No. 6: Japanese Patent Application Laid Open JP2012-73370    7. Patent Document No. 7: U.S. Patent Publication No. 2012-0235169    8. Patent Document No. 8: U.S. patent application Ser. No. 13/747,247
The disclosed subject matter has been devised to consider the above and other problems, features, and characteristics. Thus, embodiments of the disclosed subject matter can include vehicle headlights including an automatic level controller that can provide favorable light distributions for drivers with a simple structure such that does not include a movable structure as compared with the conventional headlight. The disclosed subject matter can also include a reflector type headlight including the automatic level controller, which can provide giving a glare type light to an oncoming vehicle and the like, even when vehicles incorporating the headlight including the automatic level controller suddenly incline in a direction with reference to a road due to road conditions, etc.